Magnetic recording device and magnetic recording method

Abstract

A magnetic recording device includes a magnetic recording medium, a microwave assisted magnetic head having a main magnetic pole for generating a recording magnetic field, and a spin torque oscillator provided near the main magnetic pole for generating a microwave magnetic field, a recording current supply part for supplying a recording current to recording coils according to recording current waveform data, a drive current supply part for supplying a drive current to the spin torque oscillator, and a drive current control part for controlling supply of the drive current by the drive current supply part based on the data. Taking into consideration as an indicator whether a polarity reversal interval included in the data exceeds a threshold time, the drive current control part controls the drive current supply part so as not to substantially lower the quality of signals recorded on the magnetic recording medium.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a magnetic recording device having a microwave assisted magnetic head, and a magnetic recording method.BACKGROUND OF THE INVENTION[0002]In the field of magnetic recording using a head and a medium, further improvement in performance of the magnetic recording medium and the magnetic head is demanded as the recording density of magnetic disc devices increases.[0003]A magnetic recording medium is a discontinuous medium consisting of a set of magnetic grains. The magnetic grains each have a single-domain structure. Each recording bit on a magnetic recording medium consists of a plurality of magnetic grains. Therefore, in order to increase the recording density, the magnetic grains must be smaller and the borders between adjacent recording bits must be less uneven. However, as the magnetic grains become smaller, the magnetic grains are less thermally stable in association with their reduced volume.[0004]A presumable measure to ...

AI Technical Summary

Benefits of technology

[0080]In the microwave assisted magnetic head 1 in this embodiment, magnetic flux generated as a result of a recording current being supplied from the recording current supply part 91a to the first coil 9a and second coil 9b is guided by the main magnetic pole layer 6 to the magnetic recording layer (perpendicular magnetization layer) of the magnetic disc 100 to write on while converging, whereby a recording magnetic field emerges from the end face 61a on the ABS 70 side of the main magnetic pole layer 6 (main magnetic pole part 61).

[0081]Concurrently, a drive current (direct current) IOP supplied from the drive current supply part 91b flows through the main magnetic pole layer 6 (main magnetic pole part 61), spin torque oscillator 10, and trailing shield 7 in this order. As the drive current IOP flows, magnetization of the spin injection layer 12 causes electrons to be spin-polarized. When the spin polarization rate of the spin injection layer 12 is positive, the spin electrons polarized in the opposite direction to the majority spin of the spin injection layer 12 are reflected on the spin injection layer and injected into the magnetic field generation layer 14. The reflected spin electrons act on the magnetization of the magnetic field generation layer 14 and induce magnetization precession of the magnetic field generation layer 14, whereby a microwave magnetic field is generated from the magnetic field generation layer 14. With this microwave magnetic field being superimposed on the recording magnetic field from the main magnetic pole layer 6, signals can be recorded on the magnetic disc 100 having a high magnetic anisotropy energy Ku.

[0082]Here, if a microwave magnetic field is constantly generated while signals are recorded, the problem that the microwave magnetic field assists the returning magnetic field that is the recording magnetic field returning to the trailing shield 7 (the magnetic field in the opposite direction to the recording magnetic field) and lowers the quality of signals recorded on the magnetic disc 100 (see the pri

Problems solved by technology

However, as the magnetic grains become smaller, the magnetic grains are less thermally stable in association with their reduced volume.

Therefore, if the anisotropic magnetic field of a magnetic recording medium exceeds an acceptable value determined based on the upper limit of the recording magnetic field intensity, recording on the magnetic recording medium fails.

There is a problem that the writing operation according to a recording current of a relatively long polarity re

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